Synthesis, cytotoxic activities and DNA binding properties of β-carboline derivatives

Design, synthesis and pharmacological evaluation of β-carboline derivatives as potential antitumor agent via targeting autophagy

A series of novel β-carboline derivatives was designed, synthesized and evaluated as potential anticancer agents. Among them, compound 6g showed the most potent antiproliferative activity against the 786-0, HT-29 and 22RV1 cell lines with IC₅₀ values of 2.71, 2.02, and 3.86 μM, respectively. The antitumor efficiency of compound 6gin vivo was also evaluated, and the results revealed that compound 6g significantly suppressed tumor development and reduced tumor weight in a mouse colorectal cancer homograft model. Further investigation on mechanisms of action demonstrated that compound 6g inhibited HCT116 cell growth by stimulating the ATG5/ATG7-dependent autophagic pathway. These molecules might be served as candidates for further development of colorectal cancer therapy agent.

Multicomponent synthesis of novel β-carboline-fused imidazolium derivatives via the Mannich reaction: cytotoxicity, molecular docking, and mechanistic studies as angiogenesis inhibitors

Herein we report novel multicomponent reactions for the synthesis of β-carboline-fused imidazolium derivatives via the Mannich-type reaction.

A comprehensive overview of β-carbolines and its derivatives as anticancer agents

β-Carboline alkaloids are a family of natural and synthetic products with structural diversity and outstanding antitumor activities. This review summarizes research developments of β-carboline and its derivatives as anticancer agents, which focused on both natural and synthetic monomers as well as dimers. In addition, the structure-activity relationship (SAR) analysis of β-carboline monomers and dimers are summarized and mechanism of action of β-carboline and its derivatives are also presented. A few possible research directions, suggestions and clues for future work on the development of novel β-carboline-based anticancer agents with improved expected activities and lesser toxicity are also provided.

Lacerda EDP, Lima RS, M. de Oliveira A, Camargo AJ, Napolitano HB. Molecular modeling of cytotoxic activity of a new terpenoid-like bischalcone

This study describes the synthesis and structure of (1E,4E)-1-(3-chlorophenyl)-5-(2,6,6-trimethylcyclohex-1-en-1-yl)penta-1,4-dien-3-one (BC I). This work evaluates molecular docking and cytotoxic activity against two tumor cell lines.

Synthesis and In Vitro Antitumor Activity of Novel Bivalent β-Carboline-3-carboxylic Acid Derivatives with DNA as a Potential Target

A series of novel bivalent β-carboline derivatives were designed and synthesized, and in vitro cytotoxicity, cell apoptosis, and DNA-binding affinity were evaluated. The cytotoxic results demonstrated that most bivalent β-carboline derivatives exhibited stronger cytotoxicity than the corresponding monomer against the five selected tumor cell lines (A549, SGC-7901, Hela, SMMC-7721, and MCF-7), indicating that the dimerization at the C³ position could enhance the antitumor activity of β-carbolines. Among the derivatives tested, 4B, 6i, 4D, and 6u displayed considerable cytotoxicity against A549 cell line. Furthermore, 4B, 6i, 4D, and 6u induced cell apoptosis in a dose-dependent manner, and caused cell cycle arrest at the S and G2/M phases. Moreover, the levels of cytochrome C in mitochondria, and the expressions of bcl-2 protein, decreased after treatment with β-carbolines, which indicated that 6i and 6u could induce mitochondria-mediated apoptosis. In addition, the results of UV-visible spectral, thermal denaturation, and molecular docking studies revealed that 4B, 6i, 4D, and 6u could bind to DNA mainly by intercalation.

Synthesis and in vitro cytotoxicity evaluation of β-carboline-linked 2,4-thiazolidinedione hybrids: potential DNA intercalation and apoptosis-inducing studies

A series of β-carboline-linked 2,4-thiazolidinedione hybrids was synthesized and studied for their DNA affinities and cytotoxicities. The most potent compound was 19e with IC₅₀ of 0.97 ± 0.13 μM.

Novel harmine derivatives for tumor targeted therapy

Harmine is a beta-carboline alkaloid found in medicinal plant PeganumHarmala, which has served as a folk anticancer medicine. However, clinical applications of harmine were limited by its low pharmacological effects and noticeable neurotoxicity. In this study, we modified harmine to increase the therapeutic efficacy and to decrease the systemic toxicity. Specifically, two tumor targeting harmine derivatives 2DG-Har-01 and MET-Har-02 were synthesized by modifying substituent in position-2, -7 and -9 of harmine ring with two different targeting group2-amino-2-deoxy-D-glucose (2DG) and Methionine (Met), respectively. Their therapeutic efficacy and toxicity were investigated both in vitro and in vivo. Results suggested that the two newharmine derivatives displayed much higher therapeutic effects than non-modified harmine. In particular, MET-Har-02 was more potent than 2DG-Har-01 with promising potential for targeted cancer therapy.

Interaction of an anti-cancer photosensitizer with a genomic DNA: From base pair specificity and thermodynamic landscape to tuning the rate of detergent-sequestered dissociation

A detailed characterization of the binding interaction of a potent cancer cell photosensitizer, norharmane (NHM) with a genomic DNA (herring sperm; hsDNA) is undertaken with particular emphasis on deciphering the strength, mode, dynamics, energetics and kinetics of binding. A major focus of the study underlies a successful exploration of the concept of detergent-sequestered dissociation of drug from the drug-DNA complex. Biophysical techniques such as absorption, steady-state and time-resolved fluorescence spectroscopy, circular dichroism, DNA helix melting, stopped-flow fluorescence kinetics and calorimetry have been used. A primarily intercalative mode of binding of NHM with DNA is shown. However, the overall interaction is governed by more than one type of binding forces. We demonstrate that the essential prerequisite of a slower dissociation rate of drug from DNA helix is achieved by tenable choice surfactants. Our results also highlight an effective tunability of the rate of dissociation of the DNA-intercalated drug via detergent-sequestration. A detailed isothermal titration calorimetric study unveils the key role of hydrophobic force underlying NHM-hsDNA association. This is further substantiated by the enthalpy-entropy compensation behavior. The major entropic contribution in detergent-induced dissociation of NHM from NHM-hsDNA complex is also demonstrated. Our results present not only a comprehensive structural and thermodynamic profile, base pair specificity, association kinetics for binding of NHM with DNA but also explore the thermodynamic and kinetic aspects of dissociation of bound drug. Characterization and tuning of the essential prerequisites for a drug to be efficient in anti-cancer functionality bear direct and widespread significance in contemporary global research.

Synthesis and biological evaluation of piperazine group-linked bivalent β-carbolines as potential antitumor agents

A series of bivalent β-carbolines with a piperazine group spacer between 3-methylene units were synthesized and their cytotoxic activities in vitro were evaluated. Compounds 7e and 7g exhibited potent cytotoxic activity.

Synthesis of β-carboline-benzimidazole conjugates using lanthanum nitrate as a catalyst and their biological evaluation

A series of β-carboline-benzimidazole conjugates bearing a substituted benzimidazole and an aryl ring at C3 and C1 respectively were designed and synthesized. The key step of their preparation was determined to involve condensation of substituted o-phenylenediamines with 1-(substituted phenyl)-9H-pyrido[3,4-b]indole-3-carbaldehyde using La(NO3)3·6H2O as a catalyst and their cytotoxic potential was evaluated. Conjugates 5a, 5d, 5h and 5r showed enhanced cytotoxic activity (GI50 values range from 0.3 to 7.1 μM in most of the human cancer cell lines) in comparison to some of the previously reported β-carboline derivatives. To substantiate the cytotoxic activity and to understand the nature of interaction of these conjugates with DNA, spectroscopy, DNA photocleavage and DNA topoisomerase I inhibition (topo-I) studies were performed. These conjugates (5a, 5d and 5r) effectively cleave pBR322 plasmid DNA in the presence of UV light. In addition, the effect of these conjugates on DNA Topo I inhibition was studied. The mode of binding of these new conjugates with DNA was also examined by using both biophysical as well as molecular docking studies, which supported their multiple modes of interaction with DNA. Moreover, an in silico study of these β-carboline-benzimidazole conjugates reveals that they possess drug-like properties.

Design and synthesis of C3-pyrazole/chalcone-linked beta-carboline hybrids: antitopoisomerase I, DNA-interactive, and apoptosis-inducing anticancer agents

A series of β-carboline hybrids bearing a substituted phenyl and a chalcone/(N-acetyl)-pyrazole moiety at the C1 and C3 positions, respectively, was designed, synthesized, and evaluated for anticancer activity. These new hybrid molecules showed significant cytotoxic activity, with IC50 values ranging from <2.0 μM to 80 μM, and the structure-activity relationships (SAR) associated with substitutions at positions 1 and 3 of these hybrids was clearly addressed. Further, induction of apoptosis was confirmed by Annexin V-FITC, Hoechst staining, and DNA fragmentation analysis. In addition, DNA photocleavage studies proved that two of the hybrids, (E)-1-(furan-2-yl)-3-(1-(4-(trifluoromethyl)phenyl)-9H-pyrido[3,4-b]indol-3-yl)prop-2-en-1-one (7 d) and 1-(3-(furan-2-yl)-5-(1-(4-(trifluoromethyl)phenyl)-9H-pyrido[3,4-b]indol-3-yl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone (8 d) could effectively cleave pBR322 plasmid DNA upon irradiation with UV light. Active hybrid 8 d inhibited DNA topoisomerase I activity efficiently and preserved DNA in the supercoiled form. To further corroborate the biological activities, as well as to understand the nature of the interaction of these hybrids with DNA, spectroscopic studies were also performed. Unlike simple β-carboline alkaloids, the binding mode of these new hybrid molecules with DNA was not similar, and both biophysical as well as molecular docking studies speculated a combilexin-type of interaction with DNA. Further, an in silico study of these β-carboline hybrids revealed their drug-like properties.

Synthesis and biological evaluation of novel bivalent β-carbolines as potential antitumor agents

A series of bivalent β-carbolines with a spacer between the 3-carboxyl oxygens was synthesized and their cytotoxic activities in vitro and antitumor efficacies in vivo were evaluated. Compound 22 exhibited potent antitumor activity against Lewis lung cancer in mice with a tumor inhibition rate of 64.2%.

3D-QSAR and Docking Studies of a Series ofβ-Carboline Derivatives as Antitumor Agents of PLK1

An alignment-free, three dimensional quantitative structure-activity relationship (3D-QSAR) analysis has been performed on a series ofβ-carboline derivatives as potent antitumor agents toward HepG2 human tumor cell lines. A highly descriptive and predictive 3D-QSAR model was obtained through the calculation of alignment-independent descriptors (GRIND descriptors) using ALMOND software. For a training set of 30 compounds, PLS analyses result in a three-component model which displays a squared correlation coefficient (r2) of 0.957 and a standard deviation of the error of calculation (SDEC) of 0.116. Validation of this model was performed using leave-one-out,q2looof 0.85, and leave-multiple-out. This model gives a remarkably highr2pred(0.66) for a test set of 10 compounds. Docking studies were performed to investigate the mode of interaction betweenβ-carboline derivatives and the active site of the most probable anticancer receptor, polo-like kinase protein.

Synthesis and structure--activity relationships of N²-alkylated quaternary β-carbolines as novel antitumor agents

A series of novel N(2)-alkylated quaternary β-carbolines was synthesized by modification of position-1, 2, 7 and 9 of β-carboline nucleus with various alkyl and arylated alkyl substituents, and their cytotoxic activities in vitro and antitumor potencies in mice were evaluated. Compound 3m was found to be the most potent antitumor agent. SARs analysis revealed that (1) the substituents in position-2 and 9 of β-carboline nucleus played a vital role in modulation of antitumor activity; (2) the benzyl and 3-phenylpropyl substituents in position-2 and 9 of β-carboline ring were the optimal substituents giving rise to significant antitumor agent. These compounds might be a novel promising class of antitumor agents with clinical development potential.

Design, synthesis and in vitro and in vivo antitumor activities of novel bivalent β-carbolines

A series of bivalent β-carbolines with a spacer of three to ten methylene units between the indole nitrogen was synthesized and evaluated as antitumor agents. The results demonstrated that compounds 18c, 21b, 25a and 31b exhibited strong cytotoxic activities with IC(50) value of lower than 20 μM against four tumor cell lines. Acute toxicities and antitumor efficacies of the selected compounds in mice were also evaluated, compounds 18b, 21b, 26a and 31b exhibited potent antitumor activities with tumor inhibition rate of over 40% in animal models. Preliminary structure-activity relationships analysis indicated that (1) the spacer length affected antitumor potencies, and four to six methylene units were more favorable; (2) the introduction of appropriate substituent into position-1 of β-carboline facilitated antitumor potencies.

Synthesis and evaluation of new β-carboline-3-(4-benzylidene)-4H-oxazol-5-one derivatives as antitumor agents

In the present work, we report the synthesis and in vitro anticancer and antimicrobial activity evaluation of a new series of 1-substituted-β-carboline derivatives bearing a 4-benzylidene-4H-oxazol-5-one unity at C-3. The compound 2-[1-(4-methoxyphenyl)-9H-β-carbolin-3-yl]-4-(benzylidene)-4H-oxazol-5-one (11) was the most active derivative, exhibiting a potent cytotoxic activity against glioma (U251), prostate (PC-3) and ovarian (OVCAR-03) cancer cell lines with IC₅₀ values of 0.48, 1.50 and 1.07 µM, respectively. An in silico study of the ADME properties of the novel synthesized β-carboline derivatives was also performed.

Manganese dioxide mediated one-pot synthesis of methyl 9H-pyrido[3,4-b]indole-1-carboxylate: Concise synthesis of alangiobussinine

The carboline ring system is an important pharmacophore found in a number of biologically important targets. Development of synthetic routes for the preparation of these compounds is important in order to prepare a range of analogues containing the carboline heterocyclic moiety. A manganese dioxide mediated one-pot method starting with an activated alcohol and consisting of alcohol oxidation, Pictet–Spengler cyclisation, and oxidative aromatisation, offers a convenient process that allows access to β-carbolines. This one-pot process for the preparation of methyl 9H-pyrido[3,4-b]indole-1-carboxylate has subsequently been used as the key step in the synthesis of alangiobussinine and a closely related analogue.